Methods and apparatus for applying powder to workpieces

An apparatus for use in sequentially applying an annular band of powder to a surface of each can lid of a plurality of can lids, said apparatus comprising a rotatable turret having a circular array of can lid retainers to hold can lids in a spaced apart relationship with one surface of each of said can lids facing outwardly away from an axis of rotation of said turret, said turret being rotatable to move each of said can lids in turn to and from a work station along an arcuate path, and a spray device disposed adjacent to said turret, said spray device being operable to spray an annular band of powder on one surface of each of said can lids in turn while each of said can lids is held at said work station by said turret in a spaced apart relationship with said spray assembly, said spray device including a body section in which a flow of air with powder entrained therein is conducted, a charging apparatus connected with said body section to electrostatically charge powder entrained in said flow of air in said body section, a nozzle connected with said body section and spaced apart from said one surface of each of said can lids during movement of each of said can lids in turn to and from said work station ant during spraying of an annular band of powder onto each of said can lids at said work station, said nozzle including an inner deflector element which has an outer side surface which flares outwardly in the direction of flow of the stream of air with electrostatically charged powder entrained therein and which is engaged by the flow of the stream of air with electrostatically charged powder entrained therein, said nozzle including an outer deflector element having an inner side surface which flares outwardly in the direction of flow of the stream of air with electrostatically charged powder entrained therein and which circumscribes at least a part of said outer side surface of said inner deflector element and is engaged by the flow of the stream of air with electrostatically charged powder entrained therein, said outer side surface of said inner deflector element and said inner side surface of said outer deflector element cooperating to define a flow path which has an annular cross sectional configuration and which flares outwardly in the direction of flow of the stream of air with electrostatically charged powder entrained therein, an excess powder collector at least partially enclosing said nozzle to draw a flow of excess powder away from said one surface of a can lid held at said work station by said turret and into said excess powder collector, said excess powder collector being spaced apart from said one surface of said can lid at said work station during flow of the stream of air and powder through said space between said nozzle and said one surface of said can lid at said work station and during a flow of excess powder away from said one surface of said can lid at said work station into said excess powder collector, a diverter located between said charging apparatus and said nozzle and connected with said body section to divert a flow of air and electrostatically charged powder being conducted in said body section away from said nozzle to interrupt a flow of powder from said nozzle toward said can lid at said work station while the flow path between the outer side surface of the inner deflector element and the inner side surface of the outer deflector element remains open to facilitate spraying an annular band of powder on a next succeeding can lid, a source of powder, a pump connected in communication with said source of powder and said nozzle to induce a flow of powder from said source of powder toward said nozzle, said pump being operable between an active condition in which said pump is effective to induce a flow of powder from said source of powder and an inactive condition in which said pump is ineffective to induce a flow of powder from said source of powder, and control means for effecting operation of said pump between the active condition and the inactive condition to produce pulses of air with powder entrained therein, said diverter being operable between an active condition in which said diverter is effective to divert a flow of air and powder away from said nozzle and an inactive condition in which said diverter is ineffective to divert a flow of air and powder, said control means being operable to effect operation of said diverter between said inactive condition and said active condition to divert a trailing end portion of each of said pulses of powder away from said nozzle.

An apparatus for use in sequentially applying an annular band of powder to a surface of each can lid of a plurality of can lids, said apparatus comprising a rotatable turret having a circular array of can lid retainers to hold can lids in a spaced apart relationship with one surface of each of said can lids facing outwardly away from an axis of rotation of said turret, said turret being rotatable to move each of said can lids in turn to and from a work station along an arcuate path, and a spray device disposed adjacent to said turret, said spray device being operable to spray an annular band of powder on one surface of each of said can lids in turn while each of said can lids is held at said work station by said turret in a spaced apart relationship with said spray assembly, said spray device including a body section in which a flow of air with powder entrained therein is conducted, a charging apparatus connected with said body section to electrostatically charge powder entrained in said flow of air in said body section, a nozzle connected with said body section and spaced apart from said one surface of each of said can lids during movement of each of said can lids in turn to and from said work station and during spraying of an annular band of powder onto each of said can lids at said work station, said nozzle including an inner deflector element which has an outer side surface which flares outwardly in the direction of flow of the stream of air with electrostatically charged powder entrained therein and which is engaged by the flow of the stream of air with electrostatically charged powder entrained therein, said nozzle including an outer deflector element having an inner side surface which flares outwardly in the direction of flow of the stream of air with electrostatically charged powder entrained therein and which circumscribes at least a part of said outer side surface of said inner deflector element and is engaged by the flow of the stream of air with electrostatically charged powder entrained therein, said outer side surface of said inner deflector element and said inner side surface of said outer deflector element cooperating to define a flow path which has an annular cross sectional configuration and which flares outwardly in the direction of flow of the stream of air with electrostatically charged powder entrained therein, and an excess powder collector at least partially enclosing said nozzle to draw a flow of excess powder away from said one surface of a can lid held at said work station by said turret and into said excess powder collector, said excess powder collector being spaced apart from said one surface of said can lid at said work station during flow of the stream of air and powder through said space between said nozzle and said one surface of said can lid at said work station and during a flow of excess powder away from said one surface of said can lid at said work station into said excess powder collector, a powder supply to hold powder to be sprayed by said spray device, a pump connected in communication with said powder supply and operable between an active condition inducing a flow of powder from said powder supply toward said nozzle and an inactive condition in which said pump is ineffective to induce a flow of powder from said powder supply toward said nozzle, a diverter connected with said body section and operable between an active condition in which said diverter is effective to divert a flow of powder away from said nozzle and an inactive condition in which said diverter is ineffective to divert a flow of powder away from said nozzle, and control means for effecting operation of said pump to its inactive condition and for contemporaneously therewith effecting operation of said diverter to its active condition.

An apparatus for use in sequentially applying powder to each workpiece of a plurality of workpieces, said apparatus comprising a spray device which sprays powder on each of said workpieces in turn while said workpiece is at a work station, said spray device including components which produce pulses of air with powder entrained therein, a body section connected with said components which produce pulses of air and in which a flow of pulses of air with powder entrained therein is conducted, charging elements which are connected with said body section and electrostatically charge powder entrained in the flow of pulses of air in said body section, a nozzle connected with said body section to spray powder onto each of said workpieces in turn at said work station, said nozzle being effective to spray powder in one of said pulses of air with powder entrained therein onto one of said workpieces and to spray powder in a pulse of air with powder entrained therein next succeeding said one pulse of air with powder entrained therein onto a workpiece next succeeding said one workpiece, and a diverter located upstream of said nozzle and connected with said body section to divert away from said nozzle a portion of at least some of the pulses of air with powder entrained therein, said components which produce pulses of air with powder entrained therein includes a source of powder, a pump connected with the source of powder to induce a flow of powder from said source of powder toward said nozzle, said pump being operable between an active condition in which said pump is effective to induce a flow of powder from said source of powder and an inactive condition in which said pump is ineffective to induce a flow of powder from said source of powder, and control means for effecting operation of said pump between said inactive condition and said active condition, said diverter being operable between an active condition in which said diverter is effective to divert a flow of air and powder away from said nozzle and an inactive condition in which said diverter is ineffective to divert a flow of air and powder, said control means being operable to effect operation of said diverter between said inactive condition and said active condition in a predetermined relationship with operation of said pump between said inactive condition and said active condition to enable said diverter to sequentially divert the same portion of each of said pulses of air with powder entrained therein.

An apparatus for use in sequentially applying powder to each workpiece of a plurality of workpieces at a work station, said apparatus comprising a conveyor which is operable to move each of the workpieces in turn to and from the work station, a spray device which is disposed adjacent to said conveyor and is operable to spray at least a portion of a pulse of air with electrostatically charged powder entrained therein onto each of the workpieces in turn at the work station, said spray device including pulse producing means for producing pulses of air with powder entrained therein, a body section connected with said pulse producing means and in which a flow of pulses of air with powder entrained therein is conducted, charging apparatus connected with said body section and operable to electrostatically charge powder entrained in each of the pulses of air in the flow of pulses of air with powder entrained therein, a diverter connected with said body section and operable to divert a portion of each of said pulses of air with powder entrained therein away from said body section, said diverter being operable between an active condition in which said diverter is effective to divert a flow of air and powder away from said body section and an inactive condition in which said diverter is ineffective to divert a flow of air and powder away from said body section, a nozzle connected with said body section to direct a flow of at least a portion of each of the pulses of air with powder entrained therein toward each of the workpieces in turn at the work station, and control means for effecting operation of said diverter from the active condition to the inactive condition to enable at least a portion of one of said pulses of air with powder entrained therein to be conducted through said nozzle toward one of said workpieces at the work station, for effecting operation of said diverter from the inactive condition to the active condition to divert a trailing end portion of the one pulse of air with powder entrained therein away from said body section, and for effecting operation of said diverter from the active condition to the inactive condition to enable at least a portion of a pulse of air with powder entrained therein next succeeding the one pulse to be conducted through said nozzle toward the workpiece next succeeding the one workpiece at the work station.

An apparatus for use in sequentially applying powder to a surface of each workpiece of a plurality of workpieces, said apparatus comprising a conveyor which is operable to sequentially move said plurality of workpieces to and from a work station, a source of powder, a pump connected with said source of powder, said pump being operable between an active condition in which said pump is effective to induce a flow of air with powder from the source of powder entrained therein and an inactive condition in which said pump is ineffective to induce a flow of air with powder entrained therein, control means for effecting operation of said pump between the active condition and the inactive condition to produce pulses of air with powder entrained therein, and a spray device which is disposed adjacent to said conveyor and is operable to spray powder on said surface of each of said workpieces in turn while each of said workpieces is at said work station, said spray device including a body section connected with said pump and which receives pulses of air with powder entrained therein from said pump, a charging apparatus connected with said body section to electrostatically charge powder entrained in the pulses of air in said body section, a nozzle connected with said body section and spaced apart from said surface of each of said workpieces during movement of each of said workpieces in turn to and from said work station and during spraying of powder onto each of said workpieces at said work station, a diverter connected with said body section at a location between said charging apparatus and said nozzle and operable to divert a flow of air with powder entrained therein away from said nozzle, an excess powder collector at least partially enclosing said nozzle and operable to draw a flow of excess powder away from said surface of a workpiece at the work station and into said excess powder collector, said excess powder collector being spaced apart from said surface of said workpiece at said work station and during a flow of excess powder away from said surface of said workpiece at said work station into said excess powder collector, said control means being operable to effect operation of said diverter to divert a trailing end portion of each of said pulses of air with powder entrained therein away from said nozzle.

An apparatus for use in sequentially applying powder to a surface of each can lid of a plurality of can lids, said apparatus comprising a conveyor which is operable to move can lids in a spaced apart relationship to and from a work station, and a spray device disposed adjacent to said conveyor and operable to spray powder onto a surface of each of the can lids in turn while each of the can lids is positioned at the work station by said conveyor, said spray device including a pump operable between an active condition in which said pump is operable to produce a flow of air with powder entrained therein and an inactive condition in which said pump is ineffective to produce a flow of air with powder entrained therein, a body section connected with said pump and in which a flow of air with powder entrained therein from said pump is conducted, charging elements which electrostatically charge powder entrained in the flow of air in said body section, a nozzle connected with said body section and spaced apart from the surface of each of the can lids during movement of each of the can lids in turn to and from the work station and during spraying of powder onto each of the can lids at the work station, an excess powder collector at least partially enclosing said nozzle and operable to draw a flow of excess powder away from the surface of a can lid held at the work station by said conveyor and into said excess powder collector, said excess powder collector being spaced apart from the surface of the can lid at the work station during flow of the stream of air and powder through the space between said nozzle and the surface of the can lid at the work station and during a flow of excess powder away from the surface of the can lid at the work station into said excess powder collector, a diverter connected with said body section and operable between an active condition diverting a flow of air and powder entrained therein away from said nozzle and an inactive condition in which said diverter is ineffective to divert a flow of air and powder entrained therein away from said nozzle, and control apparatus which effects repetitive operation of said pump between the active and inactive conditions to produce a series of pulses of air with powder entrained therein which also effects operation of said diverter from the inactive condition to the active condition to divert a trailing end portion of each pulse of air with powder entrained therein and to effect operation of said diverter from the active condition to the inactive condition before a leading end portion of a next succeeding pulse of air with powder entrained therein is conducted to said diverter to enable the powder in the leading end portion of each pulse of air with powder entrained therein to be applied to one of the can lids while the powder in the trailing end portion of each pulse of air with powder entrained therein is diverted by said diverter before the powder in the trailing end portion of each pulse of air with powder entrained therein can be applied to one of the can lids.